The excersise originally comes from Cuba where the boxers swings with heavy iron cast pipes, not sledgehammers, on a tire.

The pipes weigh equally through the top to the bottom and you don't get that bouncing effect the same way you do with a sledgehammer.

Instead of doing it for 10 reps - they do it for 2 minutes straight.

If you try it, lemme know how it works for you.

Hedge, This is a circuit with no more than 30secs between stations. Doing a 20lb sledgehammer swing for 2 min in the middle of a circuit or even as the second station in a six station circuit would be nearly impossible. As for the rebound on the tire? I wish there was more but there is actually very little due to it being hollow with thick sides. BUT there is just enough rebound to train both eccentric and concentric strength.